import {
  BufferGeometry,
  Float32BufferAttribute,
  LineBasicMaterial,
  LineSegments,
  Matrix3,
  Vector3
} from '../../three.module.js';

const _v1 = new Vector3();
const _v2 = new Vector3();
const _normalMatrix = new Matrix3();

class VertexNormalsHelper extends LineSegments {

  constructor(object, size = 1, color = 0xff0000) {

    let nNormals = 0;

    const objGeometry = object.geometry;

    if (objGeometry && objGeometry.isGeometry) {

      console.error('THREE.VertexNormalsHelper no longer supports Geometry. Use BufferGeometry instead.');
      return;

    } else if (objGeometry && objGeometry.isBufferGeometry) {

      nNormals = objGeometry.attributes.normal.count;

    }

    //

    const geometry = new BufferGeometry();

    const positions = new Float32BufferAttribute(nNormals * 2 * 3, 3);

    geometry.setAttribute('position', positions);

    super(geometry, new LineBasicMaterial({color, toneMapped: false}));

    this.object = object;
    this.size = size;
    this.type = 'VertexNormalsHelper';

    //

    this.matrixAutoUpdate = false;

    this.update();

  }

  update() {

    this.object.updateMatrixWorld(true);

    _normalMatrix.getNormalMatrix(this.object.matrixWorld);

    const matrixWorld = this.object.matrixWorld;

    const position = this.geometry.attributes.position;

    //

    const objGeometry = this.object.geometry;

    if (objGeometry && objGeometry.isGeometry) {

      console.error('THREE.VertexNormalsHelper no longer supports Geometry. Use BufferGeometry instead.');
      return;

    } else if (objGeometry && objGeometry.isBufferGeometry) {

      const objPos = objGeometry.attributes.position;

      const objNorm = objGeometry.attributes.normal;

      let idx = 0;

      // for simplicity, ignore index and drawcalls, and render every normal

      for (let j = 0, jl = objPos.count; j < jl; j++) {

        _v1.set(objPos.getX(j), objPos.getY(j), objPos.getZ(j)).applyMatrix4(matrixWorld);

        _v2.set(objNorm.getX(j), objNorm.getY(j), objNorm.getZ(j));

        _v2.applyMatrix3(_normalMatrix).normalize().multiplyScalar(this.size).add(_v1);

        position.setXYZ(idx, _v1.x, _v1.y, _v1.z);

        idx = idx + 1;

        position.setXYZ(idx, _v2.x, _v2.y, _v2.z);

        idx = idx + 1;

      }

    }

    position.needsUpdate = true;

  }

}


export {VertexNormalsHelper};
